1. Field of the Invention
The present invention relates to an ejector decompression device that is suitably used for a vapor compression refrigerant cycle in which high-temperature and high-pressure refrigerant compressed in a compressor is cooled in a refrigerant radiator and low-temperature and low-pressure refrigerant after being decompressed is evaporated in an evaporator. More particularly, the present invention relates to an ejector structure of an ejector cycle.
2. Description of Related Art
An ejector of an ejector cycle is a kinetic pump (JIS Z 8126(1994) No. 2.1.2.3) including a nozzle in which refrigerant is decompressed to generate a high-speed refrigerant flow, and a pressure increasing portion. In the pressure increasing portion, refrigerant is drawn by entrainment function of high-speed refrigerant (drive refrigerant) jetted from the nozzle, and pressure of refrigerant is increased by concerting speed energy to pressure energy while the drawn refrigerant from the evaporator and the drive refrigerant from the nozzle are mixed.
In the ejector cycle, pressure of refrigerant to be sucked into the compressor is increased by converting expansion energy to pressure energy in the ejector, thereby reducing motive power consumed by the compressor. Further, refrigerant is circulated into the evaporator of the ejector cycle by using the pumping function of the ejector. However, when energy converting efficiency of the ejector, that is, ejector efficiency is reduced, the pressure of refrigerant to be sucked to the compressor cannot be sufficiently increased by the ejector. In this case, the motive power consumed by the compressor cannot be sufficiently reduced.
Further, when an axial line of the nozzle is largely offset from an axial line of the pressure increasing portion, high-speed refrigerant jetted from the nozzle collides with an inner wall surface of the pressure increasing portion, and the refrigerant flow is disturbed. In this case, eddy loss is caused due to the disturbed refrigerant flow, and the ejector efficiency is decreased.